The invention relates to the fields of optical diffraction and analyte detection.
In many clinical settings the proper assessment of a patient's symptoms requires the determination and quantification of multiple analytes over a broad dynamic range. Detection technologies relying on light emission from labels often suffer from crosstalk where a strong signal originating from the binding of one analyte may drown out weaker signals. Some assay developers dilute the sample to lower the signal of the high concentration analyte, but this solution is limited in its ability to extend dynamic range as the dilution may ultimately hinder the ability to measure the analytes having lower concentrations.
In order to counter these issues, some have developed fluorophores with very distinct spectral properties, e.g., quantum dots, which must be analyzed using different excitation and emission filters. Others, such as described in U.S. Pat. No. 6,551,788, have relied on particle size differences to distinguish and quantify several analytes in one sample, adding the difficult step of controlling particle size so that analytes can be distinguished.
Other technologies such as capillary electrophoresis use a single label to resolve individual antibody-antigen complexes. All of these approaches rely heavily on cumbersome methods that may limit their application in cost-sensitive or rugged environments.
There is a need for new methods of detecting multiple analytes over a broad concentration range.